Key Takeaways
- Drain flies (those tiny fuzzy “moths” around your sink) breed in gunk inside drains, not in the water itself.
- Killing the adult flies isn’t enough — you have to clean out the slimy buildup where eggs and larvae live.
- The basic plan: find the source → scrub the drain biofilm → flush with hot water or enzyme cleaner → block re-infestation.
- Boiling water and bleach alone usually don’t solve it long-term, because larvae hide in the slime on pipe walls.
- For big or stubborn infestations (or if you suspect a broken pipe), it’s worth calling a licensed plumber or pest pro.
To get rid of drain flies, first identify which drain they’re coming from, then thoroughly clean that drain’s organic buildup, where the flies lay eggs. Scrub inside the drain with a long brush or pipe cleaner using hot, soapy water or an enzyme-based drain cleaner, then flush with very hot water. Repeat daily for about a week to break the life cycle, and keep the area dry and clean so new flies can’t breed. Simply spraying adult flies or pouring in bleach won’t work long-term unless you remove the slimy film inside the drain where larvae live.
Introduction: How to Get Rid of Drain Flies Without Losing Your Mind
If you’ve ever flipped on the bathroom light and watched a cloud of tiny fuzzy bugs hover up from the sink like they pay rent, congratulations — you’ve met drain flies.
I still remember the first time I dealt with them. I thought, “Huh, one cute little moth in the bathroom.” Two days later, that “one” had apparently started a family, a small town, and maybe a local government.
Figuring out how to get rid of drain flies isn’t just about killing the ones you see. The real action is happening in the slimy film inside your drains, where they lay eggs and the larvae feast on gunk. Until you deal with that, they’ll keep respawning like it’s a video game.
In this guide, we’ll walk through:
- How to confirm that you actually have drain flies (not fruit flies or gnats)
- The step-by-step cleanout that gets results
- Natural options vs. chemical cleaners
- How to stop them from coming back
All in real-world language, with a little humor, because if we can’t laugh while scrubbing sink slime, what are we even doing?
Step 1: Make Sure You’re Dealing With Drain Flies
Before you go nuclear on your plumbing, let’s confirm who the enemy is.
What Drain Flies Look Like
Drain flies (also called moth flies, sewer flies, sink flies) are:
- Tiny, about 1/8 inch long
- Fuzzy or hairy-looking, with moth-like wings
- Gray, tan, or brown
- Often resting on walls near sinks, tubs, or floor drains
They’re usually hanging out near drains, not over your fruit bowl.
Drain Fly vs. Fruit Fly vs. Fungus Gnat
| Feature | Drain Fly | Fruit Fly | Fungus Gnat |
|---|---|---|---|
| Body shape | Fuzzy, moth-like | Smooth, tiny, often reddish eyes | Thin, mosquito-like |
| Where you see them | Around sinks, tubs, floor drains | Around fruit, trash, wine, vinegar | Around potted plants, damp soil |
| Flight style | Short, lazy hops & flutters | Fast, zippy | Weak, slow near plants |
If they look like tiny moths stuck to the wall by your sink, you’re in the right place.
Step 2: Find the Breeding Drain (Yes, There’s Usually a Main One)
Drain flies breed in slimy organic buildup — that black/brown gunk lining pipes and traps.
Common hotspots:
- Bathroom sinks
- Shower and tub drains
- Kitchen sinks (especially with garbage disposals)
- Basement floor drains
- Laundry or utility sinks
Simple Tape Test
If you’re not sure which drain is guilty:
- At night, dry the suspected drain rim.
- Place a piece of clear tape, sticky side down, over part of the opening, leaving some gaps for airflow.
- In the morning, check the tape for stuck tiny fuzzy flies.
No flies? Try another drain the next night.
Step 3: Break the Life Cycle — Clean Out the Gunk
Here’s the core truth: if you don’t remove the organic slime, they will come back. Adults only live a couple of weeks, but they lay dozens of eggs at a time in that buildup.
Tools You’ll Want
- Long flexible drain brush or pipe brush
- Old toothbrush (for the drain cover)
- Bucket or large bowl (optional)
- Dish soap or degreasing cleaner
- Kettle or pot for very hot (not boiling) water
- Optional: enzyme-based drain cleaner (not harsh acid)
Option A: Mechanical Cleaning (Best Starting Point)
- Remove the drain cover
- Unscrew or gently pry it up, depending on the style.
- Scrub the drain walls
- Insert a long brush and scrub sides of the pipe and the P-trap area as far as you can reach.
- You’re not just moving hair; you’re scraping off that slimy brown/black film the larvae live in.
- Scrub the cover
- Clean the underside of the drain cover with hot, soapy water; it often holds plenty of goo on its own.
- Flush with hot water
- Slowly pour very hot (not boiling, to protect pipes and seals) water down the drain to rinse what you loosened.
Repeat this daily for a few days if the buildup is heavy.
Option B: Enzyme Cleaners (Gentle but Effective)
Enzyme-based drain cleaners (often marketed as “bio” or “enzymatic” drain treatments) digest organic matter instead of just burning through it like harsh chemical drain openers.
- Apply according to label directions (usually at night, then no water use for several hours).
- Use on already scrubbed drains for best effect — think of it as a “polish” after your scraping work.
- Good for ongoing maintenance to keep that biofilm from building up again.
Why Bleach and Boiling Water Alone Aren’t Enough
- Bleach may kill some larvae on the surface but doesn’t penetrate deep into slime layers or under debris.
- Boiling water can damage some pipes and usually doesn’t stay hot long enough in the entire line to solve the problem.
They’re fine as supporting acts, but not the main solution.
Step 4: Trap and Reduce Adult Drain Flies
While you’re tackling the drains, it’s satisfying to reduce the adult population so you’re not being dive-bombed in the shower.
Simple DIY Traps
- Apple cider vinegar trap
- Small bowl, a bit of apple cider vinegar, drop of dish soap, left near the affected drain.
- Attracts and drowns some adults (not specific to drain flies, but it helps).
- Sticky traps
- Yellow or clear sticky cards placed near walls and drains.
- Great for monitoring how many flies you still have.
Low-Tech Option
- A vacuum. Honestly.
- A quick pass with the hose attachment along walls and around the sink can thin the herd.
- Very satisfying, 10/10 would recommend.
Remember: traps help with adults, but the real win is always cleaning the breeding site.
Step 5: Keep Drains Clean So They Don’t Come Back
Once you’ve done the gross part, you want to stay out of infestation territory.
Ongoing Maintenance Tips
- Run hot water for 30 seconds after using sinks or tubs that tend to build up scum.
- Use a drain screen to catch hair and food scraps.
- Once a week or so, do one of the following:
- Scrub the top of the drain with an old toothbrush and dish soap.
- Use a small dose of enzyme cleaner as a preventive.
- Don’t let standing water sit in little-used drains for weeks — run water regularly or cap them.
Watch for These Warning Signs
- Persistent bad smell from a specific drain
- Slow draining even after cleaning
- Flies concentrated near one area over and over
These can indicate deeper buildup or even a pipe issue beneath the floor or slab.
When DIY Isn’t Enough: Call in a Pro
Sometimes the problem isn’t your sink habits — it’s the plumbing itself.
Call a plumber or pest control pro if:
- Flies keep coming back no matter what you do
- Multiple rooms are affected, especially with floor drains or basements
- You suspect a broken pipe, leaky trap, or hidden standing water under the house
- There’s sewage smell along with the flies
Pros can:
- Use cameras to inspect inside lines
- Check for cracked pipes or hidden leaks
- Treat areas you can’t access (like under slabs) safely
It’s not a failure; sometimes your home is just too creative in how it holds water.
Natural vs. Chemical: What Actually Works for Drain Flies?
Natural / Low-Toxicity Approaches
- Mechanical scrubbing
- Hot water flushes
- Enzyme-based cleaners
- Vinegar traps
These are usually enough for mild to moderate infestations, especially if you can reach the source drain easily.
Harsher Chemical Options
- Caustic drain openers (lye-based)
- Acidic drain cleaners
These are more about clearing clogs than dealing with drain flies and can:
- Be dangerous to handle
- Damage older pipes
- Still not fully remove the slime layer where larvae hide
If you use them, treat them as a clog fix, not your primary fly solution.
Frequently Asked Questions
If you’ve correctly identified and cleaned the breeding drain, you can usually see a big reduction within a few days. Because eggs and larvae are in stages, give it 1–2 weeks of consistent cleaning and maintenance to fully break the cycle.
Almost never. As long as there’s slimy organic buildup in a drain or hidden puddle, they keep breeding. Adult flies might die off, but new ones keep emerging until you remove the gunk they’re living in.
They’re mostly a nuisance, not a direct health threat, but they can carry bacteria from drains to nearby surfaces and food prep areas. They’re a sign that you’ve got organic buildup somewhere that needs attention, especially in kitchens and bathrooms.
Bleach may kill some larvae and microbes on contact, but it doesn’t reliably penetrate the protected slime layer along pipes. It can be a supporting step, but by itself, it usually doesn’t solve the infestation long-term.
Little-used drains are perfect for them because water sits and biofilm builds up undisturbed. Run hot water regularly in those fixtures and consider a thorough scrubbing and enzyme treatment to clear out any slime.
Summary
Getting rid of drain flies is less about buying the strongest spray and more about doing one unglamorous but crucial job: cleaning out the gunk inside your drains.
When you:
- Confirm you’re really dealing with drain flies
- Track down the breeding drain
- Scrub the walls and trap to remove the slimy organic film
- Support that with hot water, enzyme cleaners, and a few simple traps
- Keep drains clean and free of standing water
…those fuzzy little sink squatters don’t stand a chance.
It might take a week or so of consistent effort, but the payoff is big: no more bugs greeting you in the bathroom at 6 a.m., and a cleaner, fresher plumbing system overall. Your drains will be happier, and so will you.
